1. Field of the Invention
The present invention generally relates to cathode ray tubes and, more particularly, is directed to a cathode ray tube (CRT) having a color selecting electrode with an opening for displaying a color image.
2. Description of the Related Art
FIG. 1 of the accompanying drawings shows a conventional cathode ray tube of this type.
As shown in FIG. 1, a panel 11, a funnel portion 12 and a neck portion 12a, each being made of glass, constitute a tube envelope. A color selecting electrode 13 (e.g., aperture grill or the like) is disposed on the inner surface of a skirt portion 11a of the panel 11, and an electron gun 18 is disposed within the neck portion 12a.
As shown in FIG. 2, the color selecting electrode 13 comprises a metal thin plate 14 having vertical stripe-shaped opening portions 14a to serve as a grid and a metal frame 15 (15a, 15b) for giving a proper tension to the metal thin plate 14.
To the frame members 15a, 15b are secured springs 16b of long plate shape through holders 16a as supporting members 16. The color selecting electrode 13 are supported at four points by the engagement between apertures 16c of the spring 16b and pins 17 of the panel 11. In FIG. 2, reference numerals 20 designate bimetal members for correcting a so-called mislanding of an electron beam due to a thermal expansion of the color selecting electrode 13.
In the example of the conventional cathode ray tube, the springs 16b are fixed to the opposing frame members 15a, 15b in the opposite directions so that the color selecting electrode 13 is twisted due to various factors. As a consequence, a so-called landing twist occurs in an electron beam emitted from the electron gun 18.